The Direct Spectroscopy of Positronium Hyperfine Structure Using a Sub-THz Gyrotron

Positronium is an ideal system for research on Quantum Electrodynamics (QED), especially in a bound state. A discrepancy of 3.9 standard deviations has been found between the measured hyperfine structure (Ps-HFS) and the QED predictions. This may be due to the contribution of unknown new physics or common systematic effects in previous measurements, in all of which the Zeeman effect was used. We propose a new method to directly measure the Ps-HFS using a high power gyrotron. We compare two resonators which have been developed to supply sufficient power to drive the direct transition, a Fabry-Pérot resonator and a ring resonator with a diffraction grating. We plan to perform first direct measurement of Ps-HFS within the next six months.     

Characterization of vacancy-type defects and phosphorus donors introduced in 6H-SiC by ion implantation

Received: 18 February 1998/Accepted: 5 June 1998     

A regioselective enolate formation of trimethylsilylmethyl ketones application to the (E)-selective synthesis of α,β-unsaturated ketones

Two possible enolate anions of trimethylsilylmethyl ketones have been prepared regioselectively by the appropriate choice of base. The one directed to the silylmethyl site behaves as a highly reactive and (E)-selective condensation reagent to aldehydes.     

A regio- and stereo-controlled synthesis of α,β-unsaturated carbonyl compounds

α,β-Unsaturated carbonyl compounds and butenolides are readily prepared by the rhodium(I) catalyzed isomerization of 1,3-diene monoepoxides and α-alkylidene-γ-butyrolactones, respectively. The former transformation is formally regarded as the equivalent of a regiospecific aldol condensation of an unsymmetrical ketone.     

An oxidative route to α-trimethylsilyl ketones by means of rhodium catalyzed dehydrogenation of β-trimethylsilyl alcohols

The transfer hydrogenation of β-trimethylsilyl alcohols catalyzed by HRh(PPh₃)₄ has been successfully applied to the efficient synthesis of α-trimethylsilyl ketones.     

The morphology of polyethylene prepared by γ-ray-induced polymerization in various solvents

Polyethylenes were prepared by γ-ray-induced polymerization in ethyl and n-butyl alcohols, tert-butyl alcohol containing 5 vol-% of water, 2,2,5-trimethylhexane, 2,2,4-trimethylpentane, and cyclohexane in the temperature range 25–90°C. The morphology of the polymers as-polymerized and studied by electron microscopy depends on three factors through the degree of undercooling: the affinity of the solvent, polymerization temperature, and the polymer molecular weight. Large lamellar crystals are formed even in the alcohols when at least two of them are chosen properly.     

Liquid-liquid equilibria for four ternary systems containing methanol and cyclohexane

Nagata, I., 1984. Liquid-liquid equilibria for four ternary systems containing methanol and cyclohexane. Fluid Phase Equilibria, 18: 83–92.Liquid-liquid equilibria have been obtained experimentally for the systems methanol-benzene-cyclohexane, methanol-toluene-cyclohexane, methanol-acetone-cyclohexane and methanol-2-propanol-cyclohexane at 298.15 K. The experimental results are compared with predicted values obtained from the UNIQUAC and extended UNIQUAC equations.